U.S. Pat. No. 3,657,443, filed Sept. 29, 1969, by Hein Louis Klopping, and granted Apr. 18, 1972, discloses the preparation of alkoxycarbonylcyanamides (alkylcyanocarbamates) from cyanamide and alkyl chloroformates.
Berichte, 62, 1393-1394 (1929) discloses the reaction of the ethoxycarbonylcyanamide with dimethylsulfate to produce N-ethoxycarbonyl-N-methylcyanamide.
U.S. Pat. No. 3,823,179, filed Dec. 7, 1972, by Julius Jakob Fuchs, and granted July 9, 1974, discloses the reaction of N-alkoxycarbonyl-N-methylcyanamides with amine hydrochlorides followed by extraction with methylene chloride, evaporation of methylene chloride under vacuum, distillation, and subsequent reaction with isocyanate or isothiocyanate. However, the only specific examples are to instances where the alkoxy group is a methoxy group. And in the generic segment of the specification, the only disclosed process for achieving alkoxycarbonylmethylcyanamides where the alkoxy group is other than methyl is by starting with alkyl cyanamides.
U.S. Pat. No. 3,850,924, filed Apr. 5, 1973, by Julius J. Fuchs and Joel B. Wommack, and granted Nov. 26, 1974, discloses a process for making 3-cyclohexyl-1-methyl-6-dimethylamino-s-triazine-2,4(1H,3H)-dione by the following reaction sequence: ##STR2##
It has now been discovered that significant increases in the overall yield of the above-described five-step reaction sequence, and in particular, in the practical yield of said reaction sequence, can be achieved by using a chloroformate of the formula: ##STR3## where R=ethyl, n-propyl, or isopropyl, preferably ethyl.